1. Field of the Invention
The present invention relates to a swing analyzer and a golf club shaft selecting system. More specifically, the present invention relates to a swing analyzer and a golf club shaft selecting system that support selection of a kick point suitable for a user.
2. Description of the Background Art
A golf club shaft has various characteristics, and it is necessary for a golfer to select a golf club shaft having characteristics suitable for the golfer. A golf club shaft suitable for each golfer can be selected in most cases by appropriately selecting shaft mass, flex and kick point, among various characteristics of a golf club shaft. The shaft mass, flex and kick point, however can be designed independent from each other and, therefore, there are a huge number of combinations of these characteristics. This makes it very difficult to select a suitable golf club shaft for each golfer.
A golf club shaft selecting system focusing on shaft flex (EI: bending stiffness) is described, for example, in International Publication WO96/11726. Here, measurement of swing time, swing speed (club head speed), club head acceleration or amount of shaft strain of each golfer, or measurement of head speed in addition to the items above, is disclosed.
A golf club shaft selecting system focusing on bending stiffness distribution (EI distribution) of a shaft is described, for example, in Japanese Patent Laying-Open No. 2004-129687. This solution includes: a first analysis system having shaft behavior measuring means for measuring deformation behavior of a shaft during a swing, shaft EI calculating means for calculating EI distribution of the shaft, and shaft shape calculating means for calculating deformed shape of the shaft during a swing; and a second analysis system having swing classification means for analyzing and classifying a swing by a golfer. The deformation behavior of the shaft during a swing is analyzed, and the golfer's swings are analyzed, whereby an optimal shaft for the golfer is selected.
A golf club shaft selecting system focusing on distortion stiffness (torque) of a shaft is described, for example, in Japanese Patent Laying-Open No. 2001-70482. Here, measurement of shaft strain amount during a swing of each golfer, or simultaneous measurement of strain amount and head speed is disclosed.
Another exemplary method of measuring distortion strain is disclosed in Japanese Patent Laying-Open No. 2003-205053. According to the disclosure, distortion strain generated in the shaft during a golf club swing is measured, and based on time history data of measured distortion strain, dynamic evaluation of the shaft including distortion behavior of the shaft is made.
Further, a golf club shaft selecting system focusing on toe down amount during a swing is described, for example, in Japanese Patent Laying-Open No. 2003-284802. Here, a method is disclosed, in which bending moment distribution on the shaft during a swing of a sample golf club is measured, based on the measured data and the bending stiffness distribution of the shaft, five elements including the “toe down amount,” which is the amount of flexure of shaft in the direction in which the toe side of club head lowers immediately before the impact, are calculated, and based on the result of calculation, more suitable or optimal shaft for the golfer is selected.
Another exemplary method of measuring the “toe down amount” is described in Japanese Patent Laying-Open No. 10-43332. Here, use of a television camera or optical detecting means for measuring the toe down amount of a golf club is disclosed.
The conventional shaft selecting systems, however, require a high-speed camera or the like. It is impossible with a simple structure to analyze swing characteristics of a user and to select kick point suitable for the swing characteristics of the user.